This JB3D adjustable butt hook is designed for the Kral NP02. 

The hook utilises the original butt plates up and down adjustment and the angle of the wings/links can be adjusted to suit your shoulder.

To fit the hook, if not being set in the central position the adjustment button on the Kral plate needs to be removed.

It is very simple to do, push the button all the way in and then remove the spring that keeps it in place.

It can then be replaced by the spacer block provided with the hook to close up the hole that is left and the hook can now be fitted.

Fitting instructions are included.

Two arm lengths are available please see the listing photos and select Wings or Wings and Extensions from the drop down menu.